Back in 2008 Leader Technologies,a developer of internet-based system, filed a lawsuit against Facebook claiming they had infringed on one of their patents with the invention of the site. The technology in question was one which it made it possible for people to communicate on a large scale such as we do on Facebook. An ultimate jury decision found that Facebook had indeed infringed on the patent.

Yesterday we learned that the patent claim was rendered invalid by the U.S. Court of Appeals for the Federal Circuit in Washington. Their decision was largely based on the company taking too long to apply for patent protection for the technology. Typically one must seek protection within a year of offering an invention for sale. Evidence suggests Leader was peddling the technology all throughout 2002, but didn’t file for protection until December 2003.

So Facebook is off the hook with this lawsuit, but it seems there are countless others always popping-up around the social-networking giant’s technology platform. In early March Yahoo filed a claim against Facebook asserting the site had infringed on patents stemming from their research and development efforts.

Yahoo comments on the suit in a written statement:

“Yahoo! has invested substantial resources in research and development through the years, which has resulted in numerous patented inventions of technology that other companies have licensed. These technologies are the foundation of our business that engages over 700 million monthly unique visitors and represent the spirit of innovation upon which Yahoo! is built. Unfortunately, the matter with Facebook remains unresolved and we are compelled to seek redress in federal court. We are confident that we will prevail.”

Recently Yahoo updated its court filing against Facebook claiming they also infringed on several more open source technology patents from Yahoo. This brings the number of patents in question to 16. It seems there’s no end to these patent disputes.

We will keep you posted on all of Facebook’s patent wars and the upcoming public offering and IPO roadshow. In the meantime, try to figure out if there’s anything you can sue Facebook for, after all, it seems like the trendy thing to do.